QUANTITATION OF CHOLESTEROL OXIDATION-PRODUCTS IN UNIRRADIATED AND IRRADIATED MEATS

A method to detect 7-ketocholesterol, cholesterol-5beta,6beta-epoxide, cholesterol-5alpha,6alpha-epoxide, 4-cholesten-3-one, 4,6-cholestadien-3-one and 4-cholestene-3,6-dione in unirradiated and irradiated beef, pork and veal was developed by use of chloroform-methanol-water extraction, solid-phase extraction, column separation, thin-layer chromatography and gas chromatography. This method recovered 78-88% of the cholesterol oxidation products and detected the cholesterol oxidation products at 10 ppb or higher. Irradiation of the meats to a dose of 10 kGy increased these compounds, except 4,6-cholestadien-3-one for all three types of meat, over unirradiated, and except cholesterol-5alpha,6alpha-epoxide and 4-cholesten-3-one for the pork. All the cholesterol oxidation products in the unirradiated meats increased during storage at 0-4-degrees-C for 2 wk with some exceptions for the pork. The increases of cholesterol oxidation products in stored irradiated meats were greater than those in the unirradiated.